Fluid Volume Research Articles

Cystic plate approach in laparoscopic cholecystectomy: a consecutive retrospective analysis

PurposeThis study aimed to investigate the safety, feasibility, and possible advantages of the cystic plate approach during laparoscopic cholecystectomy in a retrospective cohort of surgical patients.MethodsWe summarized the key points of the technical approach, retrospectively analyzed the clinical outcomes of 156 patients in the cystic plate approach group from July 2018 to July 2023, and compared the findings with those of 173 cases in the routine approach group from the same period.ResultsWe observed no differences in the average stone size, operation time, postoperative hospital stay, conversion rate, complications, or Visual Analog Scale pain scores on the second day of surgery between the two groups (p = 0.076, 0.067, 0.278, 1.000, 0.633, and 0.131, respectively). However, intraoperative blood loss, number of clips used, volume of postoperative drainage fluid, and Visual Analog Scale pain scores on the day of surgery in the cystic plate approach group were significantly lower than those in the routine approach group (p = 0.000, 0.031, 0.027, and 0.021, respectively).ConclusionsThe cystic plate approach is a safe, feasible, and effective approach that has the advantages of minimal invasiveness with less bleeding and seepage, reduced use of biological clips, and less pain, potentially minimizing the risk of iatrogenic biliary injury. Trial registrationThis study was registered at the International Clinical Trial Registry (ChiCTR2100052860). Registration date: November 6, 2021.

Quantitative analysis of cannabinoids and metabolites in oral fluid by volumetric absorptive microsampling combined with UHPLC-HRMS.

With recent evolution of cannabis legalization around the world and multiplication of cannabis derived products, identifying and qualifying cannabis consumption has a proven interest. Although blood, plasma, and urine are common matrices widely used in toxicology laboratories, oral fluid presents specific advantages. In the context of doping tests, addiction consultation or roadside checks, where other matrices are impractical to collect or can be adulterated, oral fluid is a promising matrix that allows a non-invasive, rapid, and monitored self-sampling. However, available devices required a consequent volume of oral fluid,more than 250 µL, sometimes difficult to collect. We present here a fully optimized quantitative method for seven cannabinoids, including four metabolites, in oral fluid, Δ9-tetrahydrocannabinol, 11-hydroxy-Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol; cannabidiol, 7-hydroxy and 7-carboxycannabidiol; and cannabinol. After self-collection of 20 µL using an accurate and precise volumetric absorptive microsampling device (VAMS®), cannabinoids were derivatized with 2-fluoro-1-methylpyridinium p-toluenesulfonate to increase sensitivity. The successive steps of the proposed method, including biosampling, 1 h sample preparation with derivatization, and acquisition by ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry, were fully optimized. A limit of quantification of 0.5 ng/mL (≈10 pg per sampling) was thus targeted, adapted to the legal threshold required by the authorities and to clinical monitoring. Applied to six cannabis consumers, the proposed method made it possible to quantify in 20 µL oral fluid samples, Δ9-tetrahydrocannabinol ranging from 0.5 to 6236 ng/mL, cannabidiol from 0.6 to 190 ng/mL and cannabinol from 0.5 to 118 ng/mL.

Displaced volume versus submerged volume in the floating of a solid

Abstract This paper describes a new theoretical approach accompanied by experiments that demonstrate that the volume of the displaced fluid cannot be used to calculate the magnitude of the buoyant force when a solid object is floated in a container of only slightly larger cross-section than the object. It is important to emphasize that the discussions conducted here are accessible to high school and first-year university physics students because the concept of hydrostatic pressure and easily understood geometric considerations are applied.

Darcy–Forchheimer gravity currents in porous media

We theoretically and experimentally study gravity currents of a Newtonian fluid advancing in a two-dimensional, infinite and saturated porous domain over a horizontal impermeable bed. The driving force is due to the density difference between the denser flowing fluid and the lighter, immobile ambient fluid. The current is taken to be in the Darcy–Forchheimer regime, where a term quadratic in the seepage velocity accounts for inertial contributions to the resistance. The volume of fluid of the current varies as a function of time as $\sim T^{\gamma }$ , where the exponent parameterizes the case of constant volume subject to dam break ( $\gamma =0$ ), of constant ( $\gamma =1$ ), waning ( $\gamma <1$ ) and waxing inflow rate ( $\gamma >1$ ). The nonlinear governing equations, developed within the lubrication theory, admit self-similar solutions for some combinations of the parameters involved and for two limiting conditions of low and high local Forchheimer number, a dimensionless quantity involving the local slope of the current profile. Another parameter $N$ expresses the relative importance of the nonlinear term in Darcy–Forchheimer's law; values of $N$ in practical applications may vary in a large interval around unity, e.g. $N\in [10^{-5},10^{2}]$ ; in our experiments, $N\in [2.8,64]$ . Sixteen experiments with three different grain sizes of the porous medium and different inflow rates corroborate the theory: the experimental nose speed and current profiles are in good agreement with the theory. Moreover, the asymptotic behaviour of the self-similar solutions is in excellent agreement with the numerical results of the direct integration of the full problem, confirming the validity of a relatively simple one-dimensional model.

Intra-abdominal pressure, renal resistive index, sublingual microcirculation and total body water for guidance of volume resuscitation to avoid acute kidney injury during shock therapy

Background/objectivesShock and accompanying acute kidney injury (AKI) as a frequent complication is a well-known cause of morbidity and mortality worldwide. The current standard parameters to guide fluid resuscitation therapy (i.e., cardiac output, heart rate, blood pressure, central venous pressure) to avoid AKI and renal replacement therapy remain imprecise, and fluid overload with consequent organ oedema and high intestinal pressures result in further complications. The VoluKid study investigated additional non-invasive fluid volume parameters including assessment of total body water (TBW), renal vascular resistance [renal resistive index (RRI)], intra-abdominal pressure (IAP) and microcirculatory blood flow (MBF) to predict AKI during the first 72 h of intensive care therapy.Methods, design and analysisThis mono-centre observational cohort study included patients with shock who presented to the intensive care unit (ICU). Routine volume resuscitation parameters (i.e., cardiac output, heart rate, blood pressure, central venous pressure) were used to guide fluid therapy. In addition, four parameters, including MBF using sublingual incident dark-field microscopy, IAP, RRI assessed by duplex-sonography, and TBW using bioimpedance analysis (BIA), were measured daily and evaluated for predicting the primary outcome of acute kidney injury (AKI) and need for renal replacement therapy within the first 72 h of admission. Baseline and post-ICU admission values of these parameters were compared between patients with and without AKI.ResultsA total of 45 patients were enrolled in this study. Of those 45 patients, 37 could be followed for the entire study period of 72 h and 14 patients developed AKI (31.1%). Twelve patients (26.7%) had pre-existing renal impairment, one of whom died during the observation period. Nineteen patients (42.2%) had no renal impairment. RRI and IAP did not differ between patients with AKI and without AKI and did not predict AKI. TBW measured by BIA predicted AKI (p = 0.029). After adjustment for covariates (age, body mass index,and gender) this prediction was not significant [adjusted odds rato (OR) 0.99, p = 0.258, 95% confidence interval (CI) [0.97,1.01]]. MBF could not be estimated due a high number of missing values.ConclusionsBased on our limited data, none of the non-invasive parameters (TBA, IAP, RRI,) serve as predictors for AKI when assessed during the first 72 h after ICU admission, either when analysed separately or in combination.RegistrationClinicalTrials.gov Identifier: NCT02666404, registered 28/01/2016; URL: https://classic.clinicaltrials.gov/ct2/show/NCT02666404.

Numerical analysis of thermal and hydraulic characteristics of flow boiling in oblique interconnected microchannel heat sinks

The rising demand for efficient cooling solutions in high-performance electronics underscores the importance of microchannel heat sinks (MCHS) with interconnected channels for thermal management. Despite advancements, limited research has explored the influence of oblique interconnectors on flow distribution and their impact on optimizing thermal and hydraulic performance. This study addressed this gap by numerically investigating the hydrothermal behavior of interconnected MCHS with oblique interconnectors, using HFE-7100 as the working fluid. Six geometric configurations were compared to a baseline parallel microchannel design to determine the optimal interconnector size and orientation. The study employed the Lee mass transfer model and the Volume of Fluid (VOF) approach to capture phase-change dynamics and flow behavior under varying mass fluxes (280.4–1121.6 kg/m2s) and heat fluxes (40–60 W/cm2). The results revealed two distinct flow regimes: suction-induced flows that enhanced thermal performance and disruptive flows that impaired it. One particular design (Case 1) demonstrated superior performance with a ∼26 % higher heat transfer coefficient, ∼23 % lower thermal resistance, and a 12.45 K reduction in wall superheat relative to the baseline, though at the expense of a ∼14 % increase in pressure drop. These findings highlighted the critical role of interconnector orientation in balancing thermal and hydraulic performance, offering a design guideline for future innovations in microchannel heat sinks.

Numerical simulations of MHD effect on convective heat transfer characteristics in bubbles coalescence process

In this numerical study, the coalescence characteristic of a coaxial bubble pair and its influence on the liquid-to-wall convection heat transfer are investigated under different magnetic field intensities, magnetic field directions, and wall confinement ratios by adopting the volume of fluid (VOF) method. The results reveal that in the direction of heat flow, the toroidal vortices around the bubbles are dampened and even vanish completely after applying the spanwise magnetic fields, while the toroidal vortices only get away from the hot wall in the presence of the transverse magnetic fields. Correspondingly, the convective heat transfer on the hot wall is suppressed to varying degrees under the magnetic fields in different directions. The inhibitory action of the magnetic field on the heat transfer becomes stronger with the decreasing separation distance (s*) between the coaxial bubbles. The total increment of heat transfer (Nu*) is a decreased function of Hartmann number (Ha) and that decreased amplitude of Nu* under the spanwise magnetic field is nearly twice that of the transverse magnetic field. Additionally, the variations of Nu* are independent of the wall confinement ratio (Cr) for Ha < 400, while the Cr has an obvious effect on Nu* for Ha > 400 and the values of Nu* are considerably smaller at a larger Cr. The results about the effect of the magnetic field and wall confinement on the two-phase heat transfer can be referenced in the cooling system design of fusion reactor.

In situ static elastic properties assessment and validation with pressuremeter testing using a formation tester tool

Pressuremeter testing (PMT) is a formation test that consists of inflating a cylindrical packer inside a borehole while measuring the radial deformation or injected fluid volume as a function of packer pressure. Provided that the stiffness of the packer measuring system is known and large enough compared to that of the formation, changes in packer pressure associated with changes in injected fluid volume provide a direct measurement of formation stiffness. In turn, the in situ static shear modulus is obtained from the formation stiffness at a length scale similar to that of the packer. Here, we report on the first field-scale campaign of PMTs in deep boreholes performed using a wireline formation tester (WFT) tool. We carried out PMT measurements as part of the characterization and appraisal of potential sites for a deep geological repository for radioactive waste in Switzerland. We performed multiple PMT inflation cycles to infer in situ static shear moduli at six stations spread across four boreholes. PMT-derived static shear moduli results were consistent with static shear moduli derived from sonic logs using independent dynamic-to-static elastic moduli transformations. PMT-derived static shear moduli and laboratory-derived static elastic moduli using samples from coring performed at the depths of the PMT stations were consistent, with slightly lower laboratory values. Furthermore, we report dynamic-to-static shear moduli transformations by using laboratory-scale data obtained on cores and field-scale derived from sonic logs and PMT. We observed differences between static and dynamic shear moduli derived from laboratory scale using cores and field scale using sonic logs and PMT. We report linear trend slopes of about 0.5 for the laboratory data and 0.7 for the field data. These first results show the viability of in situ PMT in deep boreholes with a WFT tool, as it can be performed at multiple depths in a single run, in a time-efficient manner, and in combination with micro-hydraulic and sleeve fracturing stress tests for an integral approach to in situ geomechanical assessment.

Research on Propagation Characteristics of Fracture Grouting in Clay Formation

Splitting grouting is a highly effective technique for reinforcing tunnels and underground structures, ensuring their operational stability and facilitating long-term maintenance. It has been widely adopted in the prevention and remediation of geological hazards. However, the theoretical research on the diffusion mechanisms of split grouting lags behind its practical applications. This study addresses several key scientific challenges in understanding the diffusion behavior of split grouting. By integrating experimental design, numerical simulations, and theoretical analysis, we conduct a systematic investigation into the diffusion process and vein morphology of split grouting in both homogeneous and heterogeneous formations. We first employed a self-developed two-dimensional grouting test system to perform diffusion experiments on cohesive strata, focusing on the influence of various factors such as grout density, water/cement ratio, soil consistency, and fracture characteristics. The results provide insights into the diffusion patterns, morphology, soil pressure distribution, and surface uplift behavior of the grout veins. Subsequently, a numerical simulation program, developed in-house, based on the finite element method (FEM) and the volume of fluid (VOF) approach, was employed to model the entire process of fracturing grouting within clay strata. The experimental and numerical results indicate that grout vein diffusion in layered soil follows a Y-shaped pattern with an inclined deflection. In uniform strata, the surface uplift curve displays both symmetrical and asymmetrical “convex” elevations, while in heterogeneous soft and hard strata, the uplift is characterized by distinct “convex” deformations. Finally, based on these findings and the principles of contact mechanics, we analyze the underlying mechanisms. The results suggest that weak contact zones undergo tensile cracking and horizontal deflection prior to the formation of grout veins. Additionally, local stress rotations in the soil can induce tilting and deflection. The theoretical insights derived from this study provide valuable guidance for practical engineering applications.

Numerical Simulation on Flow and Heat Transfer Characteristics of a Single-loop Oscillating Heat Pipe with Variable Pipe Diameter Ratios

A three-dimensional numerical model, employing the Volume of Fluid (VOF) method, was developed for a single-loop oscillating heat pipe (OHP) with variable diameters. The investigation explored the impact of varying pipe diameter ratios on flow and heat transfer characteristics at different operational stages under a 40W heat power. The results reveal that the diameter ratio significantly affects the spatial arrangement of the evaporation, adiabatic, and condensation sections in the OHP. In the initial stage, the condensation section displays 15 liquid slugs when the diameter ratio is 1, but this number decreases to fewer than 10 in the same area when the diameter ratio exceeds 1. Comparative to a straight-pipe OHP, configurations with varying diameter ratios exhibit a marginal reduction in the average fluid velocity during the circulation of the working fluid inside the pipe, with the most pronounced velocity decrease occurring at a diameter ratio of 0.8. As the diameter ratio increases to 1.25 and 1.5, the turbulent disturbances in the region where the working fluid flows from the adiabatic section to the evaporation or condensation section intensify, facilitating the temperature exchange within the OHP. During stable operation of the OHP, the frequency of temperature oscillations increases with an increasing diameter ratio, while the amplitude decreases. Among all the cases, the OHP with a diameter ratio of 1.25 has the optimal heat resistance, 1.50K/W. The heat transfer performance of the OHP with a pipe diameter ratio of 0.8 deteriorated, and the thermal resistance increased by 27.6% compared with the straight-pipe OHP.

Numerical Analysis of the Effect of Tunnel Hydrofoil—Stern Flap on the Motion Stability of a Double M-Craft in Regular Waves

Abstract The double M-craft is a new type of high-performance multihull vessel that combines the gliding characteristics of a planing boat with the resistance-reducing characteristics of a hovercraft, but it also suffers from motion instability in regular waves. At present, there is scarce study on the effect of appendage on the motion stability of double M-craft in regular waves. By using the software star-ccm+ to numerically simulate the pitching and heaving motions of a double M-craft installed with tunnel hydrofoils and stern flaps in regular waves. Based on the overset mesh technology, the volume of fluid (VOF) method is used to capture the water–gas two-phase flow field. The 2-degree of freedom (2-DOF) motion of the rigid body is simulated by dynamic fluid-body interaction (DFBI). After investigating the effects of these combined appendages on the hydrodynamic performance, running attitude, and motion response of a double M-craft in regular waves, the optimal mounting parameters of the combined appendage have been obtained. The results have shown that all nine types of combined appendages can reduce the heave and pitch. The optimal combined appendage installation parameters include a hydrofoil longitudinal mounting position of 1/8L, an angle of attack of 3 deg, a stern flap length of 1.5%L, and a flap angle of 5 deg, which can effectively reduce the pitching response by about 8% and reduce the swaying response by about 2.6%, and enhance its longitudinal motion stability.

Anesthesia management of CRS and HIPEC in advanced ovarian cancer with ultra-high intra-abdominal pressure: a case report

Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a leading treatment for advanced ovarian cancer, significantly improving overall survival and disease-free survival. This case involves a patient with peritoneal metastasis and ultra-high intra-abdominal pressure (36 mmHg). CRS + HIPEC induces extensive pathological and physiological changes affecting respiratory, circulatory, renal, coagulation, and metabolic systems. Effective perioperative anesthesia management, including the type and volume of fluids administered, is crucial for optimizing patient outcomes. The complexities of anesthesia management in such cases present significant challenges.

Numerical investigation on dimpled target average heat transfer in free-surface water jet impingement and its enhancement effect versus flat plate target

Jet impingement serves as an effective method to enhance heat transfer in diverse industrial applications, utilizing either a separate fluid from the ambient (free-surface jet) or identical fluids (submerged jet). The target surface undergoes distinct thermal processes, featuring zones like the stagnation zone, boundary layer formation, and the transition from laminar to turbulent wall flow. However, heat transfer efficiency diminishes significantly due to pressure gradient changes beyond the stagnation zone, impeding flow and boundary layer development. Addressing this decline through surface modification techniques, such as incorporating spherical dimples, emerges as an innovative approach. This study develops a numerical model via Computational Fluid Dynamics (CFD) simulations utilizing Volume of Fluid (VOF) modeling for water jet impingement on a flat plate target. The model’s validity is established by comparing hydrodynamic and thermal aspects in both laminar and turbulent scenarios against established experimental data in literature. Nine dimpled target surfaces, featuring diverse dimensional properties and positioning configurations, are examined using this model to explore potential enhancements in heat transfer intensity. The findings indicate a notable increase in the overall surface average Nusselt number, potentially reaching up to 50% by implementing dimples in the current context. Moreover, the study highlights that the radial distribution of dimples and the non-uniform flow path ahead of the incoming fluid, which differs from parallel flat flow, result in varying effects based on dimensional properties. For instance, it has been found that modifying dimensions such as deepening dimples or altering their proximity could yield contrary effects, emphasizing the need for an optimization methodology to determine the most efficient dimpled surface setup within a given geometry.

Effect of multiple appendages on maritime surveillance ship resistance at various ship speeds

Resistance is a critical factor affecting the operational performance and economic efficiency of marine surveillance ships. To enhance the enforcement efficiency of marine surveillance ships, this study investigates the impact of five types of appendages on ship resistance performance. In this study, resistance experiments and numerical simulation calculation on the ship model were carried out. Based on Computational Fluid Dynamics (CFD) and the Volume of Fluid (VOF) method, the study captures the variations in ship resistance and the free surface Cases around the hull. A comparative analysis was then conducted on the resistance effects of different appendages installed on the ship model. It was found that the installation of stern shaft brackets, bilge keels, and ductkeel increased the ship's resistance. In contrast, the installation of spray rails reduced resistance by approximately 2.5%. However, the effectiveness of the spray rails diminished at high speeds due to their inability to prevent wave overtopping. Since stern flaps are commonly used drag-reducing appendages, this study improved the original design. Comparative analysis revealed that the modified curved structural design of the stern flaps exhibited enhanced drag reduction capabilities.

Numerical Study on the Influence of Drift Angle on Wave Properties in a Two-Layer Flow

This study examines the influence of drift angle on the wave and flow field generated by a submarine navigating through a density-stratified fluid. Employing a numerical methodology, this research computed the viscous flow field around the SUBOFF bare hull under conditions of oblique shipping maneuvers. The analytical framework relies on the Reynolds-Averaged Navier–Stokes (RANS) equations, supplemented by the Re-Normalization Group (RNG) k-ε turbulence model and the Volume of Fluid (VOF) method. The initial phases of this study involved verifying grid convergence and the accuracy of the numerical methods used. Subsequently, numerical simulations were performed across a spectrum of drift angles while maintaining a fixed Froude number of Fn = 0.5, with submergence depths set at 1.1 D and 2.0 D. The analysis focused on the wave profiles at both the free surface and the internal surface. The results indicate that the presence of a drift angle produces significant alterations in the characteristics of the free surface and internal surface when compared with straight-ahead motion. Specifically, the asymmetry in the flow field is enhanced, and the variability in the roughness of the free surface is pronounced.

Dynamic characteristics of wave entry for a deep-sea mining vehicle: Numerical and experimental studies

The deep-sea mining vehicle (DSMV) experiences complex impacts upon the wave entry, which directly affects the safety and reliability of the whole deployment system. In this paper, a computational fluid dynamics (CFD) method is proposed to investigate hydrodynamic properties and wave-entry effects of a DSMV with varying laying speeds. Firstly, a fifth-order Stokes surface gravity wave simulating Sea State 4 conditions is constructed based on the volume of fluid (VOF) method. Then, the overset mesh scheme is utilized to establish the multiple degree-of-freedom (DOF) model of DSMV which bears the traction loads of laying cable. Laboratory prototype tests are conducted, and the captured results of cavitation evolution and motion properties corroborate the present model. Numerical results indicate that the DSMV entering the wave danger point will experience hydrodynamic forces several to dozens of times greater, severely threatening structural safety. During the wave entry process, two phases of nonlinear deceleration occur, posing a risk to the umbilical cable. Surge and pitch motions caused by waves and structural asymmetry may lead to deployment position deviation. Based on the trends observed in the simulation data, guidance for deployment operations has been proposed.

Characterization of Morphological Brain Changes in Generalized Epilepsy Using Region-based Morphometry

Magnetic Resonance Imaging has been widely involved in detecting morphological brain changes in generalized epilepsy at voxel level. It is believed that region-based morphometry could provide better characterizations for macro structural changes in the brain with comparative advantages than voxel-based morphometry. The aim of this study is to detect regional brain changes associated with generalized epilepsy and to test the potential of regional brain changes in classification of patients with generalized epilepsy and non-epileptic subjects. 45 patients and 46 non-epileptic subjects were scanned using a 3 Tesla MRI scanner and 3D T1 weighted images were obtained. Images were pre-processed and region based structural metrics (grey matter volumes, white matter volumes, cerebrospinal fluid volumes, cortical gyrification, and sulcus depth) were developed using Computational Anatomical Toolbox (CAT12). Two sample t-tests were used to perform the univariate analyses and results were corrected for multiple comparisons (FDR corrected, p &lt; 0.05). Grey matter volume reductions were detected in cerebellum, frontal lobe, temporal lobe, thalamus, and hippocampal region while bilateral white matter volume reductions were reported in cerebellum. In contrast, cerebrospinal fluid volume increments in left lateral ventricle were also detected. Reduced regional gyrification was detected in left posterior ramus of the lateral sulcus and reduced sulcal depths were detected in occipital pole, cuneus, and posterior ramus of the lateral sulcus in patients. Furthermore, pattern analysis revealed that each metric shows different discriminative abilities to distinguish patients with generalized epilepsy and non-epileptic subjects (Classification accuracy: 61.1%, 62.2%, 58.8%, 61.1% and 60% for GMV, WMV, CSFV, Cortical gyrification and sulcal depth respectively). In conclusion, this study provides a comprehensive understanding about regional structural changes (cortical and subcortical) associated with generalized epilepsy under region-based morphometry. However, pattern analyses do not provide adequate discriminative power and therefore the clinical utility of findings is limited.

Predictive model and optimization of micromixers geometry using Gaussian process with uncertainty quantification and genetic algorithm

Abstract Microfluidic devices are gaining attention for their small size and ability to handle tiny fluid volumes. Mixing fluids efficiently at this scale, known as micromixing, is crucial. This article builds upon previous research by introducing a novel optimization approach in microfluidics, combining Computational Fluid Dynamics (CFD) with Machine Learning (ML) techniques. Our research focuses on enhancing global optimization techniques while minimizing computational costs. It draws inspiration from a Y-type micromixer, initially featuring cylindrical grooves on the main channel's surface and internal obstructions. Simulations, conducted using OpenFOAM software, evaluate the impact of circular obstructions on mixing percentage and pressure drop, considering variations in obstruction diameter and offset. A Gaussian Process (GP) was utilized to model the data, providing model uncertainty. This study optimizes geometries by using genetic algorithm (GA) based on the reduced order model provided by GP. Results align with previous research, showing that medium-sized obstructions (137 mm diameter, 10 mm offset) near the channel wall are optimal. This approach not only provides efficient microfluidic optimization with uncertainty quantification but also highlights the effectiveness of combining CFD and ML techniques in achieving desired outcomes.

Separation Time of Aluminothermic Reduction Products for Sustainable Silicon Production

Background This work was carried out within the framework of the SisAl Pilot project, which is devoted to the environmentally friendly production of silicon. This new method relies on the aluminothermic reduction of quartz in slag, offering a more sustainable alternative to the traditional reduction of silica with carbon in submerged arc furnaces. Methods The process takes place in a rotary kiln producing silicon (Si) and alumina slag (actually, a CaO – Al2O3 slag), which must be separated at the end to extract the silicon. This separation process is analyzed through mathematical modelling and numerical simulation, as it is of industrial interest to know how much time it takes for Si and CaO – Al2O3 slag to separate once the process has ended. Generally, a multiphase flow model is used to estimate the separation time of the two components once aluminothermic reduction has ended. Results Several scenarios are considered for the numerical simulation of the separation time, namely different initial configurations and material properties of both fluids are covered. Moreover, the separation times obtained with two distinct multiphase flow models -VOF (volume of fluid) and Eulerian- are compared. Conclusions The separation times resulting from simulations using the multiphase Eulerian model are more realistic compared to those from the VOF model, which clearly tends to underestimate separation times. Furthermore, apart from the selected multiphase flow model, the density difference between silicon and alumina slag plays a critical role in determining the separation time.

Effect of liquid flux on wetting behavior in slender trickle bed reactors: A particle-resolved direct numerical simulation study

Slender trickle beds play a crucial role in various industrial processes involving gas-liquid-solid systems. Understanding the wetting characteristics is vital for optimizing their performance and efficiency. In this study, we employ a particle-resolved Computational Fluid Dynamics approach combining the Volume of Fluid (VoF) method for gas-liquid interactions and a second-order implicit Immersed Boundary Method (IBM) for fluid-solid interactions. The particle wettability is modeled by imposing a contact angle boundary condition at the gas-liquid-solid interface. The impact of the liquid flux on the wetting patterns and the rate of liquid penetration depth within the slender trickle bed is studied. The results show two main mechanisms of penetration through the bed: gravitation and inertia driven. The penetration of the liquid in the bed is driven by gravity when the liquid flux is low and the inertia is diminished in the top of the bed. This results in enhanced wetting from the onset of the penetration. If the inertia is high (high liquid flux), the initial liquid penetration is fast and spreading in the bed only occurs after full penetration of the bed.